Thursday, October 28, 2010

Cooler Climate May Hit N. America, Europe Next Decade

Shifting ocean currents could throw some cold water on global warming over the next decade, a new study suggests.

Europe and North America may soon experience chillier temperatures, thanks to natural North Atlantic variations that could temporarily mask the effects of human-driven, or anthropogenic, climate change.

"We believe that ocean currents and systems could, in the short term, change global warming patterns and even mean temperatures," said Noel Keenlyside of the Leibniz Institute of Marine Sciences in Kiel, Germany.

Keenlyside explained that since record keeping began in the 19th century, the North Atlantic climate has changed in natural cycles that last a decade or more.

A new forecasting model, based on past and present sea surface temperatures, suggests the imminent onset of a cool-down cycle for currents in both the North Atlantic and tropical Pacific.

Keenlyside and colleagues, whose study appears in this week's issue of the journal Nature, hope to further quantify this effect and incorporate it into future climate predictions on the decade scale.

"I think it's just naive to think that there won't continue to be multi-decadal fluctuations in the [ocean] climate," he said.

Temporary Change

Ocean current systems move heat around the globe, but they do not remain static. Their fluctuations are largely driven by seawater density, which is in turn governed by factors like temperature and salinity.